Censys expands queries to provide additional functionality. For example, the query a:zmap.io
executes a DNS lookup and expands to ip:18.104.22.168.
Your query was changed from:
parsed.names: (dns_names or maillist-manage.in)
parsed.names: (dns_names OR maillist-manage.in)
If this isn't what you intended, you can run your raw query without expansion.